The Stage 3 assembled BR1-13 package is right for you if you are looking to make big power with a power adder such as Nitrous, Turbo, or a Supercharger! We came out with this package for customers that want maximum valve train control and longevity for high cylinder pressures and temperatures. NOT ALL VALVES ARE CREATED EQUAL! We use Victory Titanium Intake valves with CRN coating to prevent corrosion associated with todays racing fuels. Titanium is the lightest material you can buy that does not compromise the strength and heat resilliancy needed in a max effort built. Then intake valves also come with a hardened tip so NO LASH CAPS NEEDED! These heads are professionally assembed to include vacuum test on Serdi guide and seat machine, Spring pressures verified and install height set, valve stem heights set to equal lengths to assure the same pushrod length and even preload amongst all lifters which is critical in short travel lifters. Heads include Mueller Performance/Victory1 or Ferrea Custom Intake valves, Ferrea Inconel Exhaust valves, and BTR .685 lift springs with Titanium Retainers